The present invention generally relates to a compact fluorescent lamp and a method for manufacturing such lamp and more particularly, relates to a compact fluorescent lamp that can be fabricated by adhesively bonding planar glass plates together forming a hermetically sealed chamber having interior partitions therein dividing a chamber cavity into a plurality of sub-chambers with fluid communication thereinbetween such that a maximum length of passageway for an electrical discharge may be achieved resulting in an improved brightness of the lamp, and a method for manufacturing such lamp.
Fluorescent lamps that utilize a fluorescent coating in a glass tube and a gas filling capable of being charged to produce ultraviolet energy in order to energize the fluorescent coating have been used for a long time. The conventional fluorescent lamps are normally supplied in the form of elongated tubes of significant length, for instance, between 2 ft and 4 ft, that require a large installation space and large fixtures for holding such lamps. Due to the bulkiness of the lamps and the fixtures, conventional fluorescent lamps have only been used in industrial or commercial applications where available space for installation is not a problem. The consumer or home usages of the fluorescent lamps are limited to the 1 ft length lamps normally used in a reading lamp fixture, or the 4 ft lamps normally used in a shop light fixture. The energy saving aspect of the fluorescent lamps has therefore not been fully utilized in the consumer market, mainly due to its bulkiness and its low light intensity (or low lumen output), when the lamps are fabricated in a package that is small enough to fit inside a consumer-type light fixture.
In more recent years, there is a significant push for the use of more compact fluorescent lamps for replacing the conventional incandescent lamps caused by a high awareness of energy savings. One other benefit for using the fluorescent lamps is the longer life time of the lamps when compared to the incandescent lamps. More compact fluorescent lamps became available which are shaped in a plurality of parallelly extending tubes from a base at a predetermined length.
One obvious drawback of the compact fluorescent lamps that must be overcome before the lamps can be widely used in the consumer market is the low lumen output when compared to that from the incandescent lamps. For instance, in a conventional 20 watt straight tube fluorescent lamp which produces approximately the same lumen output as a 100 watt incandescent bulb, 4 ft length of the fluorescent lamp is required. This is the type of straight tube fluorescent lamps that are normally used in shop light fixtures. In order to produce a higher lumen output, the arc discharge length (or simply known as the discharge length), required for producing such lumen output must be maximized which leads to the problem of packaging a long tube within a small package size such that it fits in a conventional incandescent lamp fixture.
Lamp manufacturers have extended the length of the respective tube portions in a lamp envelope, or alternatively increased the number of the tube portions to as many as eight such tube portions arranged side-by-side. One example of such application produced fluorescent lamps by bending segments of glass tubings into U-shapes and sealing of one or both legs and then connecting two or more of such bent tubes with glass bridges by simultaneously blowing out a small hole near one end of the tube and then fusing them together. For instance, in a dual U-shaped lamp, the arc discharge passageway goes up one leg, down the other and then through the glass bridge into a second bent tube arrangement.
One of such designs for fluorescent lamps is shown in U.S. Pat. No. 5,252,890 and in FIGS. 1Axcx9c2B. FIGS. 1Axcx9c1B shows a compact type fluorescent lamp device that has a crooked arc path. A reversed W-shaped arc bulb 10 which includes a first U-shaped bulb 12 and a second U-shaped bulb 14. The reverse W-shaped arc bulb 10 is fabricated in the following manner. First, the outside surface of one of the ends 16 of the first U-shaped bulb 12 and the corresponding surface of one of the ends 18 of the second U-shaped bulb 14 are heated. The heated portions are closely opposed and connected to one another in a blow-off process to fluidly communicate to each other. As shown in FIG. 1B, a first electrode 20 is disposed in one end 22 of the first U-shaped bulb 12, and a second electrode 24 is arranged in the other end 26. A substantially W-shaped arc path is thus formed in the connected first and second U-shaped bulbs 12 and 14.
As shown in FIG. 1B, a wide recess 28 is formed at the center of the pedestal portion 30 of the base 32. To house the connected portion of the first and second U-shaped bulbs 12 and 14. The process further requires the formation of a pair of holes 32 and 34 at the opposite sides of the wide recess 28 in the pedestal portion 30. The other ends 22 and 26 of the first and second U-shaped bulbs 12 and 14 in which the first and second electrodes 20 and 24 are disposed are respectively inserted into the corresponding holes 32 and 34, and are further supported with an elastic bonding agent which is later filled in the pedestal portion 30. The reversed W-shaped arc bulb 10 therefore requires elaborate manufacturing steps for blowing-off portions of the glass tubes and then reconnecting them to provide fluid communication between the two U-shaped bulbs. It is an expensive manufacturing process and the product produced must be marketed at a high cost basis.
In another embodiment, also disclosed in U.S. Pat. No. 5,252,890, a first, second, third and fourth straight bulbs 36, 38, 40 and 42 are rectangularly arranged on pedestal portion 30 of the base 32 extending perpendicularly from the pedestal portion 30. The extended end portion 36a of the first bulb 36 is connected to the extended end portion 38a of the second bulb 38 by a first connecting tube 44 to provide fluid communication between the two bulbs. This is shown in FIG. 2B. The base portion 36b of the first bulb 36 is disposed in a first hole 46a formed in the pedestal section 30 of the base 32. The base end portion 38b of the second bulb 38 which is opposite to the extended end portion 38a is disposed in a second hole 46b formed in the pedestal portion 30. The inner side surface of the second bulb 38, facing the third bulb 40, in the vicinity of base end portion 38b is connected to the corresponding portion of the third bulb 40 by a second connecting tube 48. This is shown in FIG. 2B. The second bulb 38 and the third bulb 40 are thus in fluid communication with each other. The extended end portion 40a of the third bulb 40 is connected to the corresponding portion 42a of the fourth bulb 42 by a third connecting tube 50 to enable fluid communication with each other. The base end portion 40b of the third bulb 40 is disposed in a third hole 46c formed in the pedestal portion 30, while the base end portion 42b of the fourth bulb 42 is disposed in a fourth hole 46d in the pedestal portion 30. A first electrode 52 is supported in the base end portion 36b of the first bulb 36, and a second electrode 54 is supported in the base end portion 42b of the fourth bulb 42. A relatively long arc path is therefore established through the first bulb 36, the first connecting tube 44, the second bulb 38, the second connecting tube 48, the third bulb 40, the third connecting tube 50 and the fourth bulb 42.
In this conventional construction of multiple-tube design, three separate passageways must be provided in connecting the four tubes together such that a single arc path can be obtained. The building of the four individual tubes and the connections must be made thereinbetween render the manufacturing process difficult and costly.
It is therefore an object of the present invention to provide a compact fluorescent lamp for illumination that does not have the drawbacks or shortcomings of the conventional compact fluorescent lamps.
It is another object of the present invention to provide a compact fluorescent lamp for illumination that can be fabricated in mass production at low cost.
It is a further object of the present invention to provide a compact fluorescent lamp for illumination wherein the lamp may be formed by planar glass plates.
It is another further object of the present invention to provide a compact fluorescent lamp for illumination wherein the lamp may be formed with low cost sodium glass.
It is still another object of the present invention to provide a compact fluorescent lamp for illumination wherein a plurality of sub-chambers are formed in a hermetically sealed chamber such that a maximum discharge length can be obtained by an arc going through the sub-chambers.
It is yet another object of the present invention to provide a compact fluorescent lamp for illumination capable of producing higher lumen output than conventional compact flourescent lamps.
It is still another further object of the present invention to provide a compact fluorescent lamp wherein a lamp chamber may be divided into four, six, nine, twelve or fifteen sub-chambers for achieving a maximum discharge length and lumen output.
It is yet another further object of the present invention to provide a method for fabricating a compact fluorescent lamp for illumination by utilizing planar glass plates of sodium glass material which are glued together by using a sealing glass, or glass frit, for simple and low cost assembly of the lamp.
It is still another further object of the present invention to provide a method for fabricating a compact fluorescent lamp for illumination wherein a flourescent powder is coated on the interior walls of the lamp by electrostatic coating or screen printing, while outwardly facing surfaces are also coated with a reflective coating material.
In accordance with the present invention, a compact fluorescent lamp for illumination and a simple, low cost method for fabricating such lamps are disclosed.
In the preferred embodiment, a compact fluorescent lamp for illumination may be provided which includes a lamp body constructed by two side walls, two end walls, a cover and a base forming a hermetically sealed chamber cavity, at least one interior partition within the chamber cavity forming at least two sub-chambers, the at least one interior partition has at least one aperture therethrough for providing fluid communication between the at least two sub-chambers, the at least one aperture is positioned on the at least one partition in such a way that a maximum length of passageway by a subsequently generated electrical discharge is achieved in said at least two sub-chambers, at least one chemical substance coated on the interior walls including the at least one interior partition and the inside surfaces of the two sidewalls, two end walls, the cover and the base, the chemical substance produces visible light when energized by ultraviolet energy, a pair of spaced-apart electrodes each situated in a different sub-chamber of the at least two sub-chambers for providing an electrical discharge in the at least two sub-chambers, and a gas filling the at least two sub-chambers which when charged by the electrical discharge emits ultraviolet energy to energize the at least one chemical substance coated on the interior walls for producing visible light.
The compact fluorescent lamp may be constructed by sidewalls, end walls, cover and base which have a planar surface. The planar surface may have either a rectangular or a square shape. The lamp may have at least two interior partitions within the chamber cavity forming four sub-chambers. The lamp may further include three apertures with one provided on each of three partitions which divide the four sub-chambers, the three apertures are positioned such that a maximum length of passageway by the electrical discharge is achieved in the four sub-chambers. The chamber may further have at least three interior partitions within the chamber cavity to form six sub-chambers.
The compact fluorescent lamp may further include five apertures with one provided on each of five partitions which divide the six sub-chambers, the five apertures are positioned such that a maximum length of travel by the electrical discharge is achieved in the six sub-chambers. The lamp may also have at least four interior partitions within the chamber cavity forming nine sub-chambers. The lamp may further include eight apertures with one provided on each of seven partitions which divide the nine sub-chambers, the eight apertures are positioned such that a maximum length of travel by the electrical discharge is achieved in the nine sub-chambers.
The chemical substance used in coating the interior walls in the chamber cavity may be a phosphor-containing substance. The chemical substance produces a visible light which may be daylight, special white light, cool white light or white light depending on the specific type of the chemical substance selected. The chemical substance may be coated on the interior walls by either an electrostatic coating method or a screen printing method. The compact fluorescent lamp may further include reflective coating layers placed on outwardly-facing interior walls in the lamp for improving its brightness. The sidewalls, end walls, cover, base and interior partitions may be formed of sodium-containing glass, and may be assembled together by adhesive means. The adhesive means utilized may be a sealing glass material, or a glass frit. The at least two sub-chambers may further include twelve sub-chambers which are formed by planar sodium glass plates.
The present invention is further directed to a method for fabricating a compact fluorescent lamp for illumination which includes the steps of first providing two sidewalls, two end walls, a cover and a base formed of planar glass plates, then assembling the sidewalls, end walls, cover and base together by adhesive means into a hermetically sealed chamber which also includes the step of dividing a cavity in the chamber into at least two sub-chambers by at least one interior partition formed of planar glass plates, the at least one interior partition has at least one aperture therethrough for providing fluid communication between the at least two sub-chambers, the at least one aperture is positioned on the at least one partition in such a way that a maximum length of passageway by a subsequently generated electrical discharge is achieved in the at least two sub-chambers, interior walls on the planar glass plates are coated with at least one chemical substance that produces visible light when excited by ultraviolet energy, then providing a pair of spaced-apart electrodes in the at least two sub-chambers with one electrode in each sub-chamber for generating an electrical discharge, then filling the at least two sub-chambers with a gas which emits ultraviolet energy when charged by the electrical discharge, and generating ultraviolet energy in the gas and energizing the at least one chemical substance to produce visible light.
The method for fabricating a compact fluorescent lamp may further include the step of assembling the sidewalls, end walls, cover and base together by gluing with a glass frit. The method may further include the step of providing the sidewalls, end walls, cover, base and the at least one interior partition in a rectangular or square shape. The method may further include the step of positioning the pair of spaced-apart electrodes at two extreme ends of the maximum length of passageway for the electrical discharge generated in the at least two sub-chambers. The method may further include the step of coating all interior walls that face outwardly away from the chamber with a reflective coating. The at least one chamber substance may be a powder that emits fluorescent light when excited by an electrical discharge.
The method may further include the step of dividing the cavity in the chamber into four sub-chambers by at least two interior partitions, or the step of dividing the cavity in the chamber into six sub-chambers by at least three interior partitions, or the step of dividing the cavity in the chamber into nine sub-chambers by at least four interior partitions.
The method for forming a compact fluorescent lamp may further include the step of coating the at least one chemical substance by an electrostatic coating method or by a screen printing method. The method may further include the step of providing the planar gas plates in sodium glass.